Novel alpha-glucosidase inhibitor, pradimicin Q

ABSTRACT

The present invention relates to a novel α-glucosidase inhibitor, pradimicin Q, having the following formula ##STR1## and its pharmaceutically acceptable base salts.

BACKGROUND OF THE INVENTION

The present invention relates to a benzo[a]naphthacene compound having α-glucosidase inhibiting activity. The compound of the present invention is therefore useful as human and animal medicament for the treatment of conditions in which it is desirable to suppress α-glucosidase action, or to inhibit the increase of blood glucose level; such conditions include, for example diabetes, prediabetes, obesity, and adiposity.

Recently, Japanese Kokai 2-83351, published Mar. 23, 1990, reported the isolation of a novel α-glucosidase inhibitor from fermentation broth of Actinomycetes Strain MH193-16F4. The inhibitor, benanomicin C, has the following structure formula ##STR2##

Although benanomicin C also possesses a benzo[a]naphthacene ring nucleus, its substituents differ substantially from those of the compound of the present invention. Furthermore, the compound of the present invention exhibits unexpectedly high α-glucosidase inhibitory activity compared to benanomicin C.

SUMMARY OF THE INVENTION

The present invention provides a novel α-glucosidase inhibitor designated pradimicin Q having the formula (I) ##STR3## and its pharmaceutically acceptable base salts.

Another aspect of the present invention provides a process for producing pradimicin Q which comprises cultivating a strain of pradimicin Q producing Actinomadura verrucososoora subsp. neohibisca under submerged and aerobic conditions in a medium containing assimilable sources of carbon and nitrogen, and recovering from said medium pradimicin Q.

A further aspect of the present invention provides a pharmaceutical composition comprising pradimicin Q and a pharmaceutically acceptable vehicle.

Yet a further aspect of the present invention provides a method for inhibiting an increase in blood glucose level in an animal, including humans, which comprises administering to said animal in need of such treatment a therapeutically effective amount of pradimicin Q.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present invention provides the compound pradimicin Q and its pharmaceutically acceptable base salts. "Pharmaceutically acceptable base salts" includes, but is not limited to, salts formed with inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, calcium carbonate, magnesium hydroxide, and the like, or with organic bases such as diethylamine, ethylenediamine, triethylamine, ethanolamine, and the like.

Pradimicin Q is produced by cultivating pradimicin Q producing strain of Actinomadura verrucosospora subsp. neohibisca, or a variant thereof, or a mutant thereof, in a medium containing sources of assimilable carbon and nitrogen.

A strain capable of producing pradimicin Q is Actinomadura verrucosospora subsp. neohibiscastrain R103-3. Another pradimicin Q producing strain is a mutant strain, herein designated as strain A10102, derived from strain R103-3. The characterizing properties of both strains are provided hereinbelow.

A. Producing Organism

(i) Strain R103-3 was isolated from a soil sample collected in Puerto Viejo Costa, Peru. A biologically pure culture of strain R103-3 was deposited with the American Type Culture Collection, Rockville, Md. under accession number ATCC 53930. This culture has been accepted for deposit under the BUDAPEST TREATY ON THE INTERNATIONAL RECOGNITION OF THE DEPOSIT OF MICROORGANISMS FOR THE PURPOSES OF PATENT PROCEDURE.

The morphological, cultural, physiological, and chemotaxonomical characteristics of strain R103-3 are similar to those of Actinomadura verrucosospora, but strain R103-3 is differentiated from Actinomadura verrucosospora in the formation of red diffusible pigments and other physiological characteristics Therefore, strain R103-3 was designated Actinomadura verrucosospora subsp. neohibisca subsp. nov.

(a) Morphology

Strain R103-3 forms short or rudimental aerial mycelium and well-branched non-fragmentary substrate mycelium. Loop or spiral short spore-chains (5-12 spores per chain) are formed on the aerial hyphae. The spores are oval (0.8×1.2-1.5 μm), non-motile, and have a warty surface.

(b) Cultural and Physiological Characteristics

The cultural and physiological characteristics were examined by the methods of Shirling and Gottlieb (Int. J. Syst. Bacteriol., 1966, 16:313-340), and Gordon, et al. (J. Gen. Microbiol.,1978, 109:69-78).

Strain R103-3 forms aerial mycelium and spore-chain in ISP media Nos. 3, 4, 5, and 7 and produces abundantly reddish diffusible pigments (pradimicins) in Czapek's agar and natural organic media, such as ISP medium No. 2. Cultural and physiological characteristics are shown in Tables 1 and 2, respectively.

                  TABLE 1                                                          ______________________________________                                         Cultural Characteristics of Strain R103-3                                                          Aerial                                                                         Myce-    Substrate                                                                              Diffusible                                Medium     Growth   lium     Mycelium                                                                               Pigment                                   ______________________________________                                         Sucrose-nitrate                                                                           Moderate None     Very deep                                                                              Very deep                                 agar (Czapek-                red (14)                                                                               purplish                                  Dox agar)                            red (257)                                 Tryptone-yeast                                                                            Poor, not                                                                               None     Deep red                                                                               Moderate                                  extract broth                                                                             turbid            (13)    red (15)                                  (ISP No. 1                                                                     Yeast extract-malt                                                                        Good     None     Very deep                                                                              Very dark                                 extract agar                 red (14)                                                                               red (17)                                  (ISP No. 2)                                                                    Oatmeal agar                                                                              Moderate Moder-   Moderate                                                                               Grayish                                   (ISP No. 3)         ate; pale                                                                               pink (5)                                                                               pink (8)                                                      pink (7)         to light                                                                       grayish                                                                        red (18)                                  Inorganic salts-                                                                          Moderate Poor;    Moderate                                                                               Light                                     starch agar         white    pink (5)                                                                               grayish                                   (ISP No. 4)                          red (18)                                  Glycerol-  Poor     Poor;    Colorless                                                                              None                                      asparagine          white                                                      agar (ISP No. 5)                                                               Peptone-yeast                                                                             Good     Scant;   Grayish Very deep                                 extract-iron agar   white    pink (8)                                                                               red (14)                                  (ISP No. 6)                  to deep                                                                        red (13)                                          Tyrosine agar                                                                             Moderate Poor;    Moderate                                                                               Light                                     (ISP No. 7)         white    red (15)                                                                               yellowish                                                                      pink (28)                                 Glucose-   Poor     None     Colorless                                                                              Light                                     asparagine                           pink (4)                                  agar                                                                           Nutrient agar                                                                             Moderate Poor;    Dark pink                                                                              Dark red                                                      white    (6)     (16)                                      Bennett's agar                                                                            Good     None     Blackish                                                                               Blackish                                                               red (21)                                                                               red (21)                                  ______________________________________                                          Observation after incubation at 28° for 3 weeks.                        Color Name: ISCCNBS colorname charts.                                    

                  TABLE 2                                                          ______________________________________                                         Physiological Characteristics of Strain R103-3                                 ______________________________________                                         Decomposition of:   Acid Production from*:                                     Adenine     -       Adonitol        -                                          Casein      +       D-Arabinose     -                                          Hippuric acid                                                                              +       L-Arabinose     +                                          Hypoxanthine                                                                               -       Cellobiose      +                                          Tyrosine    +       Dulcitol        -                                          Xanthine    -       Erythritol      -                                          Decarboxylation of: D-Fructose      +                                          Benzoate    -       D-Galactose     -                                          Citrate     -       D-Glucose       +                                          Mucate      -       Glycerol        -                                          Succinate   +       Inositol        -                                          Tartrate    -       Lactose         -                                          Production of:      D-Mannitol      +                                          Amylase     -       D-Mannose       -                                          Esculinase  +       D-Melezitose    -                                          Gelatinase  +       Melibiose       -                                          Nitrate reductase                                                                          +       Methyl-α-glucoside                                                                       -                                          Tyrosinase  -       Raffinose       -                                          Urease      -       L-Rhamnose      +                                          Growth in:          D-Ribose        +                                          Lysozyme, 0.001%                                                                           -       Salicine        +                                          NaCl, 1%-7% +       Soluble starch  +                                           8%         -       D-Sorbitol      -                                          pH, 5.8-11.0                                                                               +       L-Sorbose       -                                          25° C.-39° C.                                                                +       Sucrose         +                                          22° C. and 42° C.                                                            -       Trehalose       -                                                               D-Xylose       +                                          ______________________________________                                          *Basal Medium: PridhamGottlieb medium (ISP No. 9), omitted                     CuSO.sub.4.7H.sub.2 O                                                    

(c) Chemotaxonomy

The whole cell hydrolyzate of strain R103-3 contains meso-diaminopimelic acid, glucose, and madurose. Hence, the strain belongs to cell wall type III and sugar pattern B. The phopholipids contain phosphatidylglycerol and phosphatidylinositol without nitrogenous phospholipids and, hence, is placed in type P-I.

(d) Taxonomic Position

Based on the morphology and chemotaxonomy of strain R103-3, the strain is placed in the genus Actinomadura. Among hitherto described known species of Actinomadura. strain R103-3 is physiologically most similar to Actinomadura verrucosospora, but it is differentiated from the latter in its production of red diffusible pigment, resistance to NaCl, and negative acid formation from glycerol, lactose, and trehalose. Thus, strain R103-3 Was designated Actinomadura verrucosospora subsp. neohibisca subsp. nov.

Strain R103-3 is also distinct from Actinomadura hibisca known producer of pradimicins. Table 3 shows the differential characteristics of Actinomadura hibisca strain P157-2 (ATCC No. 53557) and strain R103-3 ATCC No. 53930.

                  TABLE 3                                                          ______________________________________                                         Differential Characteristics of Actinomadura                                   verrucosospora Subsp. neohibisca Strain R103-3 from                            Actinomadura hibisca Strain P157-2                                                           Strain R103-3                                                                            Strain P157-2                                          ______________________________________                                         Morphology:                                                                    Spore-chain     Short, hook Long, straight                                     Spore surface   Warty       Smooth                                             Cultural and physiological                                                     characteristics:                                                               Tyrosine agar:                                                                 Brownish pigment                                                                               Not Formed  Formed                                             Glucose-asparagine agar:                                                       Growth          Poor        Abundant                                           Reddish pigment Scant       Abundant                                           Utilization of:                                                                L-Arabinose     +           -                                                  D-Mannitol      +           -                                                  L-Rhamnose      +           -                                                  D-Xylose        +           -                                                  ______________________________________                                    

(ii) Strain A10102 is derived from strain R103-3 by mutation using N'-methyl-N'-nitro-N-nitrosoguanidine (NTG). A biologically pure culture of A10102 was deposited with the American Type Culture Collection under accession number ATCC 55092. This culture has been accepted for deposit under the BUDAPEST TREATY ON THE INTERNATIONAL RECOGNITION OF THE DEPOSIT OF MICROORGANISMS FOR THE PURPOSES OF PATENT PROCEDURE. The procedure for mutation of strain R103-3 and for the screening of the mutant strains is described below.

Strain R103-3 was grown at 28° C. for 14 days on a modified Bennett's agar consisting of soluble starch 0.5%, glucose 0.5%, fish meat extract 0.1%, yeast extract 0.1%, NZ-case 0.2%, NaCl 0.2%, CaCO₃ 0.1%, and agar 1.6%; pH 7.0. Spores of the strain were suspended in saline, dispersed by sonication for 20 seconds in ice-bath, harvested by centrifugation at 3,500 rpm for 10 minutes at 25° C., and resuspended in 10 mM Tris-HCl, pH 9.0. The spore suspension (3 ml) was mixed with 3 ml of NTG solution (5,000 μg/ml in a mixture of water-dimethyl sulfoxide 9:1 (v/v)). The mixture was gently shaken at 28° C. for 1 hour. The NTG-treated spores were harvested by centrifugation, resuspended in saline, spread on a new agar plate, and incubated at 28° C. for 7 days. Each colony was picked up, inoculated to a fresh agar plate, and incubated at 28° C. for 7 days to be used as a mother culture plate. Each culture was transferred to 10 ml of the vegetative medium (Medium A) consisting of Na L-glutamate 0.1%, L-methionine 0.05%, L-arginine 0.05%, soluble starch 1.0%, glucose 1.0%, (NH₄)₂ SO₄ 0.01%, K₂ HPO₄ 0.6%, MgSO₄.7H₂ O 0.05%, NaCl 0.05%, CaCO₃ 0.3%, salt solution (FeSO₄.7H₂ O 0.1 g, ZnSO₄.7H₂ O 0.1 g, MnCl₂.4H₂ O 0.1 g, in 1 liter of water) 1% v/v, pH 7.0. The culture was incubated at 28° C. for 14 days on a shaker operating at 200 rpm. Pradimicin Q was identified by silica gel TLC (Merck) using a solvent system of methyl acetate/n-propanol/28% ammonium hydroxide (45:105:60), Rf for pradimicin Q was 0.2-0.25. As a result of the screening, a mutant strain designated as A10102 was found to produce pradimicin Q as its major fermentation product.

(a) Morphology

Both parent and its mutant strains form tufts of loop or spiral short spore-chains (5 to 10 spores per chain) on the short aerial mycelium. The spores are oval (0.8×1.3 μm), non-motile, and have a warty surface.

(b) Cultural Characteristics

Unlike parental strain R103-3, mutant strain A10102 produces reddish-purple pigments in ISP Media Nos. 2, 3, and 7 and brownish-black pigment in ISP Medium No. 6 (Table 4).

                  TABLE 4                                                          ______________________________________                                         Characterization of Cultural Differences                                       Among R103-3 and A10102                                                        Cultural                                                                       Characteristics                                                                               Strain R103-3                                                                              No. A10102                                          ______________________________________                                         Malt extract-                                                                             G       +++; Very   ++; Blackish                                    yeast extract      dark red    red (21)                                        agar (ISP No. 2)   (17)                                                                   A       None        None                                                       D       Very deep   Very dark pur-                                                     red (14)    plish red (260)                                 Oatmeal agar                                                                              G       ++; Pinkish ++; Reddish                                     (ISP No. 3)        white (9)   purple (241)                                               A       Scant; white                                                                               Scant; white                                               D       Pinkish white                                                                              Light reddish                                                      (9)         purple (240)                                    Inorganic salts-                                                                          G       +; Pale yel-                                                                               +; Light reddish                                starch agar        lowish pink purple (240)                                    (ISP No. 4)        (31)                                                                   A       Scant; white                                                                               Scant; white                                               D       Pale yellowish                                                                             Light reddish                                                      pink (31)   purple (240)                                    Peptone-yeast                                                                             G       ++; Grayish +++; Brownish                                   extract-iron       red (19)    black (65)                                      agar (ISP No. 6)                                                                          A       None        None                                                       D       None        Brownish black                                                                 (65)                                            Tyrosine agar                                                                             G       ++; Moderate                                                                               ++; Pale reddish                                (ISP No. 7)        yellowish   purple (244)                                                       pink (28)                                                              A       Poor; white Poor; white                                                D       Pale yellowish                                                                             Pale reddish                                                       pink (31)   purple (244)                                    Glucose-   G       ±; Colorless                                                                            ±; Colorless                                 asparagine agar                                                                           A       None        None                                                       D       None        None                                            ______________________________________                                          Observation after incubation at 28° C. for 2 weeks.                     Color Name: ISCCNBS colorname charts.                                          Abbreviations: G, growth (+++ good, ++ moderate, + poor, ± scant) and       reverse color; A, aerial mycelium; and D, diffusible pigment.            

(c) Physiological Characteristics

Mutant strain A10102 shows almost the same physiological reactions as the parental strain (Table 5).

                  TABLE 5                                                          ______________________________________                                         Physiological Characteristics of                                               Strains R103-3 and A10102                                                                   Strain R103-3                                                                             Strain A10102                                          ______________________________________                                         Hydrolysis of:                                                                 Gelatin        +                +                                              Soluble starch -                -                                              Potato starch  -                -                                              Production of:                                                                 Nitrate reductase*                                                                            -/+              -/+                                            Utilization of**:                                                              Glycerol       +       (w)      -                                              D-Arabinose    -                -                                              L-Arabinose    +                +                                              D-Xylose       +                +                                              D-Ribose       +                +                                              L-Rhamnose     +                +                                              D-Glucose      +                +                                              D-Galactose    +       (w)      +     (w)                                      D-Fructose     +                +                                              D-Mannose      -                -                                              L-Sorbose      -                -                                              Sucrose        -                -                                              Lactose        -                -                                              Cellobiose     +                +                                              Melibiose      -                -                                              Trehalose      +                +     (w)                                      Raffinose      -                -                                              D-Melezitose   -                -                                              Soluble starch +                +     (w)                                      Cellulose      -                -                                              Dulcitol       -                -                                              Inositol       -                -                                              D-Mannitol     +                +                                              D-Sorbitol     -                -                                              Salicin        +                +                                              ______________________________________                                          *Czapek's sucrosenitrate broth/Peptonenitrate broth.                           **Basal Medium: PridhamGottlieb medium.                                        +(w): Weakly Positive; -/+: Marginal Utilization                         

B. Antibiotic Production

Strains R103-3 and A10102 produce the novel compound pradimicin Q, along with other pradimicins A, B, C, D, E and L, when cultivated in a conventional medium. The producing organism is grown in a nutrient medium containing known nutritional sources for actinomycetes, i.e., assimilable sources of carbon and nitrogen added with optional inorganic salts and other known growth factors. Submerged aerobic conditions are preferably employed for the production of large quantities of antibiotic, although surface cultures and bottles may also be used for production of limited amounts. The general procedures used for the cultivation of other actinomycetes are applicable to the present invention.

The nutrient medium should contain an appropriate assimilable carbon source, such as ribose, glucose, sucrose, and cellobiose. As a nitrogen source, ammonium chloride, ammonium sulfate, urea, ammonium nitrate, sodium nitrate, etc., may be used either alone or in combination with organic nitrogen sources, such as peptone, meat extract, yeast extract, corn steep liquor, soybean meal, cotton seed meal, etc. There may also be added, if necessary, nutrient inorganic salts to provide sources of sodium, potassium, calcium, ammonium, phosphate, sulfate, chloride, bromide, carbonate, zinc, magnesium, manganese, cobalt, iron, and the like.

Production of the antibiotic complex comprising pradimicin components may be effected at any temperature suitable for satisfactory growth of the producing organism, e.g., 25°-40° C., and is most conveniently carried out at a temperature of around 27°-32° C. Ordinarily, optimum antibiotic production is obtained by flask fermentation after shaking with incubation periods of 5 to 12 days. If fermentation is to be carried out in tank fermentors, it is desirable to use a vegetative inoculum in a nutrient broth from a slant culture or a lyophilized culture. After obtaining an active inoculum in this manner, it is aseptically transferred to the fermentation medium in a tank fermentor Antibiotic production in tank fermentors usually reached a maximum after 3-6 days of incubation. Agitation in the tank fermentor is provided by stirring, and aeration may be achieved by injection of air or oxygen into the agitated mixture. Antibiotic production was monitored by HPLC followed with spectroscopic techniques, or by a conventional biological assay.

Pradimicin complex thus produced may be recovered from the fermentation broth, and pradimicin Q of the present invention separated, by any suitable methods for such recovery and separations; examples of these methods include extraction, precipitation, chromatography, and other art recognized conventional techniques. A preferred isolation and purification sequence for pradimicin Q is given in Examples 2 and 3.

It is to be understood that, for the production of pradimicin Q, the present invention is not limited to the particular organisms mentioned above but includes the use of variants and mutants thereof that retain the antibiotic-producing capability. Such variants and mutants can be produced from parent strains by various means, such as X-ray radiation, UV-radiation, and chemical mutagens, such as N-methyl-N'-nitro-N-nitrosoguanidine.

Thus, another aspect of the present invention provides a method for producing pradimicin Q which comprises cultivating an antibiotic-producing strain of Actinomadura verrucosospora subsp. neohibisca under submerged and aerobic conditions in a medium containing assimilable carbon and nitrogen sources. Preferably, the antibiotic-producing strains are strain R103-3, ATCC No. 53930, and strain A10102, ATCC No. 55092.

α-Glucosidase Inhibitory Activity

Forty μl of α-glucosidase (Sigma G-5003 #11 U/mg protein) (0.1 mg/ml in 100 mM phosphate buffer, pH 6.8=0.44 U/assay) for tests (or the buffer for the control), 950 μl of 0.7 mM p-nitrophenyl-α-D-glucopyranoside (Sigma N1377), and 10 μl of the assay compound (various concentrations dissolved in DMSO) were mixed and incubated at 37° C. for 15 minutes. To the reaction mixture, 1.0 ml of 0.2N NaOH and then 1.0 ml of n-butanol were added and voltex-mixed. Absorbance of n-butanol layer at 415 nm was measured by spectrophotometer. α-Glucosidase inhibitory activity was expressed as the IC₅₀ (μg/ml), the concentration at which the test compound inhibits 50% of the enzyme activity. IC₅₀ was determined from a standard curve of p-nitrophenol released when the assay was run without the test compound (0% inhibition) and when the assay was run without the enzyme (100% inhibition).

Results

Pradimicin Q showed the strongest α-D-glucosidase activity with an IC₅₀ value of 3 μg/ml. This value is significantly higher than that for benanomicin C which showed an IC₅₀ value of 62 μg/ml. In contrast, pradimicins A and L and N,N-dimethylpradimicin FA-2, all active as antifungal compounds, have no α-glucosidase inhibitory activity.

                  TABLE 6                                                          ______________________________________                                         Compound            IC.sub.50 (μg/ml)                                       ______________________________________                                         Pradimicin A        >100                                                       N,N-dimethylpradimicin FA-2                                                                        >100                                                       Pradimicin L        >100                                                       Benanomicin C         62                                                       Pradimicin Q          3                                                        ______________________________________                                    

It is apparent that the compound of the present invention exhibit high α-glucosidase inhibitory action. Pradimicin Q is, therefore, useful for inhibiting an increase in blood glucose in animals, including humans, and for treating animals, including humans suffering from conditions such as prediabetes, diabetes, obesity and adiposity.

Pradimicin Q is administered to the animal in need of such treatment in a therapeutically effective amount by any accepted routes, including intravenous, intramuscular, oral, intranasal, and for superficial infections, topical administration. Preferably, the compound of the invention is administered parenterally or orally. Preparations for parenteral administration include sterile aqueous or non-aqueous solutions, suspensions, or emulsions. They may also be manufactured in the form of sterile solid compositions which can be dissolved in sterile water, physiological saline, or some other sterile injectable medium immediately before use. Oral formulation may be in the form of tablets, gelatin capsules, powders, lozenges, syrups, and the like. For topical administration, the compound may be incorporated into lotions, ointments, gels, creams, salves, tinctures, and the like. Unit dosage forms may be prepared using methods generally known to those skilled in the art of pharmaceutical formulations.

It will be appreciated that, when treating a host according to the method of this invention, the actual preferred route of administration and dosage used will be at the sound professional discretion of the attending physician and will vary according to the severity of the condition to be treated, route of administration, and patient characteristics, such as age, body weight, rate of excretion, concurrent medications, and general physical condition.

EXAMPLE 1 Production of Pradimicin Q by Fermentation of Actinomadura verrucosospora subsp. neohibisca

A. Agar Slant

Actinomadura verrucosospora subsp. neohibisca strain R103-3 (ATCC No. 53930) was propagated on an agar slant of modified Bennett's medium at 28° C. for 14 days. The composition of the medium is soluble starch (Nichiden Kagaku) 0.5%, glucose 0.5%, fish meat extract (Mikuni Kagaku Sangyo) 0.1%, yeast extract (Oriental Yeast) 0.1%, NZ-case (Sheffield) 0.2%, NaCl 0.2%, CaCO₃ 0.1%, and agar 1.6%.

B. Seed Culture

A small portion of the microbial growth from the slant culture was inoculated to a 500-ml Erlenmeyer flask containing 100 ml of the vegetative medium consisting of soluble starch (Nichiden Kagaku) 1%, glycerol 1%, yeast extract (Oriental Yeast) 1%, peptone (Daigo Eiyo) 0.5%, NaCl 0.3%, and CaCO₃ 0.2%. The pH of the medium was adjusted to 7.0 before autoclaving. The seed culture was incubated at 28° C. for 7 days on a rotary shaker at 200 rpm.

C. Flask Fermentation

A 5 ml portion of the seed culture was transferred to a 500-ml Erlenmeyer flask containing 100 ml of the production medium (FR-17) consisting of soluble starch (Nichiden Kagaku) 1%, glucose 1%, sodium L-glutamate 0.1%, L-methionine 0.05%, L-arginine 0.05%, (NH₄)₂ SO₄ 0.1%, MgSO₄.7H₂ O 0.05%, NaCl 0.05%, CaCO₃ 0.3%, K₂ HPO₄ 0.6%, and salt solution 1% (v/v) (FeSO₄.7H₂ O 0.1 g, ZnSO₄.7H₂ O 0.1 g, and MnCl₂.4H₂ O 0.1 g in 1 liter of water). The pH of the medium was adjusted to 7.0 before autoclaving. The fermentation was carried out at 28° C. for 14 days on a rotary shaker (200 rpm). Antibiotic production in the fermentation broth was determined spectrophotometrically. The production of total pradimicin reached a maximum at 290 μg/ml on day 11.

EXAMPLE 2 Isolation of Pradimicin Q - Method 1

The fermentation broth pooled from fifty 500-ml Erlenmeyer flasks containing 100 ml broth in each flask was centrifuged at 5,000 rpm for 10 minutes at room temperature. The supernatant (4.5 L) was adjusted to pH 2.0 with 6N HCl and mixed with ethyl acetate (2 L). Ethyl acetate layer was washed twice with H₂ O (200 ml each) and concentrated to dryness to give a crude solid (453 mg). The crude solid was dissolved in CH₃ CN-0.15% KH₂ PO₄, pH 3.5 (1:1), and applied on a column of ODS-A60 (200 ml, Yamamura Chemical Lab.) which had been equilibrated with the same solvent mixture Elution was carried out with the same solvent mixture. Fractions containing the pradimicin Q monitored by HPLC were pooled and concentrated to give a purple-red solid (190 mg). This solid (50 mg) was dissolved in 2 ml of MeOH-H₂ O (3:2) and subjected to a column of Sephadex LH-20 eluting with the same solvent mixture A yellow-red powder (27 mg) was obtained as a free form. Purity of the compounds was determined by HPLC and was over 98%. The physico-chemical properties of pradimicin Q are given in Table 7.

                  TABLE 7                                                          ______________________________________                                         Physico-Chemical Properties of Pradimicin Q                                    ______________________________________                                         Nature:            Purple-Red Powder                                           M.P. (dec.):       >200° C.                                             HR FAB(+)-MS m/z (M+H):                                                                           Found 465.0811                                                                 (Calcd: 465.0800)                                           Molecular Formula: C.sub.24 H.sub.16 O.sub.10                                  UV λmax nm (ε)                                                  in MeOH:           229(25,600), 288(19,500),                                                      514(13,200)                                                 in 0.01N HCl-50% MeOH:                                                                            232(25,800), 289(20,600),                                                      512(14,000)                                                 in 0.01N NaOH-50% MeOH:                                                                           242(20,000), 305(19,600),                                                      549(15,900)                                                 IR (KBr) cm.sup.-1 :                                                                              3197, 1712, 1600, 1488, 1399,                                                  1245, 1187                                                  .sup.1 H NMR(400MHz, DMSO-d.sub.6) δ:                                                       2.50(s), 6.97(s), 4.55(dd,                                                     J=9.8 & 4.3), 2.66(dd, J=                                                      15,8 & 9.8), 3.10(dd, J=                                                       15.8 & 4.3), 6.63(d, J=                                                        2.4), 7.24(d, J=2.4)                                        .sup.13 C NMR(100 MHz DMSO-d.sub.6)δ:                                                       187.5(s), 185.7(s), 171.5                                                      (s), 165.5(s), 164.5(s),                                                       156.0(s), 155.0(s), 153.9                                                      (s), 146.1(s), 140.2(s),                                                       137.0(s), 134.9(s), 131.6                                                      (s), 119.2(s), 118.4(s),                                                       118.3(d), 115.3(s), 110.6                                                      (s), 109.1(s), 108.5(d),                                                       108.2(d), 66.2(d), 30.7                                                        (t), 21.6(q)                                                ______________________________________                                    

EXAMPLE 3 Isolation of Pradimicin Q - Method 2

The fermentation broth (600 ml) was centrifuged at 5,000 rpm, and the supernate was applied on a column of HP-20 (200 ml). The resin was washed with water followed with acetone-H₂ O (3:2). Fractions containing compound Q were pooled and concentrated to dryness (1.4 g crude powder). The solid (170 mg) was dissolved in CH₃ CN-H₂ O (1:4) and applied on a column of ODS-A60 (200 ml). The resin Was washed with CH₃ CN-H₂ O (1:1). Fractions containing pradimicin Q were concentrated to dryness (27 mg powder). This solid (25 mg) was applied on a column of Sephadex LH-20 (70 ml) eluting with a mixture of MeOH-H₂ O (1:1, pH 8.5). A yellow-red powder (6.3 mg) was obtained as a sodium salt form. Compound Q showed weak antibacterial activity against Bacillus subtilis PCI-219 (125 μg/ml) and cytotoxic activity against mouse melanoma B16 cells with IC₅₀ at 75 μg/ml.

EXAMPLE 4 Production of Pradimicin Q by Fermentation of Strain A10102 (ATCC No. 55092)

Strain A10102 was grown in a 500-ml Erlenmeyer flask containing 100 ml of the vegetative medium consisting of soluble starch (Nichiden Kagaku) 1%, glycerol 1%, yeast extract (Oriental Yeast) 1%, peptone (Daigo Eiyo) 0.5%, NaCl 0.3%, and CaCO₃ 0.2%. The pH of the medium was adjusted to 7.0 before autoclaving. The seed culture was incubated at 28° C. for 7 days on a rotary shaker at 200 rpm.

A 5 ml portion of the seed culture was transferred to a 500-ml Erlenmeyer flask containing 100 ml of the production medium consisting of glucose 3%, Protein S (soybean flour, Ajinomoto) 3%, yeast extract 0.1%, CaCO₃ 0.3%, pH 7.0. The fermentation was carried out at 28° C. for 11 days on a rotary shaker at 200 rpm. Identification of pardimicin Q was done employing silica gel TLC (Merck) using a solvent system of MeOAc-n PrOH-28% NH₄ OH (45:105:60). Rf for pradimicin Q: 0.2-0.25 (cf pradimicin L: 0.35-0.4). From the TLC pattern, pradimicin Q was seen as the major product in the fermentation broth of strain A10102. 

What is claimed is:
 1. A compound having the formula ##STR4## and its pharmaceutically acceptable base salts.
 2. A pharmaceutically composition which comprises the compound of claim 1 and a pharmaceutically acceptable vehicle. 